rxkad: remove warnings from der-protos.h

der-protos.h was generated from Heimdal headers which in turn were
auto-generated.  The included a large number of function prototypes
of the form

  ret-type func(parm-list, type */* comment */);

where the combination of */* is ambiguous.  Does it mean an end comment
followed by a pointer declaration or a pointer declaration followed by
a begin comment.  This combination generates warnings on Windows.  The
bug was fixed in Heimdal's code generator.  Fixing it here by editing
the code.

Change-Id: Ie66a5c70b0144173d70433adfbe3ed453672af81
Reviewed-on: http://gerrit.openafs.org/10101
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>